1. Field of the Invention
The invention relates to a device for the delivery of paste-like substances, particularly sausage stuffing, for producing a pulsation-free conveying flow homogeneous with respect to its density.
2. Description of the Related Art
A device of this type is known in numerous construction variations. Thus, to be taken from DE-GM 88 05 548.5, is a vane pump for the delivery of paste-like substances which comprises a conveying apparatus with a pump chamber bounded by a base or bottom part and a cover part and arranged within a casing having an inlet port or opening and an outlet port or opening. A rotor housed within the pump chamber is driven to rotate therein and has plate-shaped slides. These are guided to move in a radial direction while being kept in contact with the radial inner wall by means of their radial boundary edges over at least part of one revolution. The axial boundary edges of the slides engage in a sealingly sliding manner between the bottom part and the cover part, the slides thus including conveying cells between them. According to this structure, the conveying cells which produce the conveying pressure, are formed essentially as annular segments. This geometric form results from the rotor rotating while being mounted essentially centrally within a cylindrical casing. The separation of the inlet and outlet ports is effected by means of a wedge segment, which is inserted in a filling manner directly behind the outlet opening in the circular space between the casing and the rotor whilst sealing with respect to these elements. The corresponding control of the slides occurs by means of a stationary central cam which allows for a supporting, as well as a releasing, control of the slides.
Sausage stuffing usually has the characteristic of being compressible. At the same time, the degree of compressibility varies in accordance with the type of stuffing and can assume values of up to 10 %. Consequently, the substance admitted into the conveying cells is inhomogeneous, although the filling process is normally supplemented by the use of vacuum. This, however, has a negative effect on the dosing accuracy.
Consequently, it is usual to provide pre-compression in the region in which the conveying pressure is being built-up in order to raise the compressibility of the sausage stuffing. In the embodiment of the device according to the prior art, this is achieved through a slight eccentricity of the rotor within the casing, which eccentricity has its maximum in the region of the vane pump building-up the conveying pressure. The eccentricity is defined such that the maximum of the narrowing of the conveying cells corresponds to the greatest known compressibility of the type of stuffing to be conveyed.
If other kinds of stuffing of less compressibility are to be handled, pressure peaks results which far exceed the filling pressure and which could create a considerable burdening of the entire system which will have a severe negative influence on the wear behavior, in particular.
3. Object of the Invention
Thus, it is the principal object of the invention to overcome the drawbacks of the prior art structure by suggesting an apparatus enabling applicability for a broad variety of stuffing types.
It is a particular object of the present invention to suggest equipment for a delivery assembly such as initially described, which enables a restriction of the pre-compression pressure.